1. Field of the Invention
This invention relates to a technique of fluidized coating, having a rotatable perforated disk.
2. Related Art Statement
A fluidized granulating and coating apparatus has heretofore been widely used in many fields for granulating and coating foodstuff, pharmaceutical preparations, feedstuff, detergents, cosmetics, toners, catalysts and the like. However, such disadvantages have been presented that, when used as a granulating apparatus, granulaited particles have low bulk densities, forms of the particles are undetermined, a distribution of particle sizes is wide and so forth, and, when used as a coating apparatus, the coating efficiency is low, material to be coated tends to be collapsed, coated film is not dense and so forth.
Therefore, in order to obviate these disadvantages, and further, to improve the production efficiency, various improved apparatuses have been proposed, and some of them have been pratically used.
For example, Japanese Patent Publication No. 54-11263 and Japanese Patent Application Laid-Open No. 60-7930 propose that fluidizing air is blown out in the tangent direction to a fludizing chamber so that the blown-out fluidizing air becomes a spiral flow, while a perforated disk at the bottom of the fluidizing chamber is kept fixed. The apparatus of 54-11263 has even an agitator. However, these are apparatuses for granulating and drying, so that the pertinency as a coating apparatus is not clear.
There have been proposed many apparatuses wherein a perforated disk is made rotatable. Japanese Patent Application Laid-Open No. 62-258734 shows an apparatus provided with a rotatable disk having a ventilation net, and Japanese Patent Publication No. 63-33900 shows a combination of a rotatable perforated disk, which is provided with small holes as usual, and an agitating bar.
Both are apparatuses for mixing, granulating, drying, disintegrating and so forth.
Furthermore, Japanese Patent Application Laid-Open No. 61-165577 shows an apparatus wherein a perforated disk, through which fluidizing air is blown out in the tangent direction, is rotated. This apparatus is also a granulating and drying machine.
As a coating apparatus provided with a rotatable perforated disk, there can be listed ones disclosed in Japanese Patent Publications Nos. 63-2212, 63-2213, 60-25182, 61-8734, 61-8735 and 61-8736, and Japanese Patent Application Laid-Open No. 59-95924 and so forth.
Out of these, the apparatus disclosed in Japanese Patent Publication No. 63-2213 is one including a special rotatable disk, which has an inclined surface, and a disintegrating rotor, and Japanese Patent Publication Nos. 63-2212 and 63-25182 disclose a rotatable disk comprising multi-layer rings as a mechanism for blowing out air outwardly through slits between the rings. Japanese Publication No. 61-8734 relates to an apparatus wherein agitating blades are provided above a rotatable disk. Japanese Patent Publication No. 61-8735 relates to an apparatus having a disintegrating device. Japanese Patent Publication No. 61-8736 relates to an apparatus wherein air passing through perforations of a rotatable disk and air passing through a slit formed between the disk and the wall of the apparatus are controlled independently of each other. And, Japanese Patent Application Laid-Open No. 59-95924 relates to an adjusting mechanism for air passing through the above-described slit. Apparatuses in which some or all techniques of the above-described four inventions are suitably combined together have been sold in the market and widely used.
Out of the conventional apparatuses described above, the apparatuses disclosed in Japanese Patent Publications Nos. 63-2213 and 61-8735 include the special rotatable disks which require high costs for manufacture and the disintegrating device must be operated, so that these apparatuses are not so suitable for coating.
Furthermore, in the apparatuses disclosed in Japanese Patent Publications Nos. 63-2212 and 60-25182, it is intended that air flows through the substantially whole surface of the rotatable disk except for the central portion, whereby, in fact, almost all air is blown out from the inner area where particles are thinly distributed due to the centrifugal force of the rotation (a blow-through phenomenon), so that fludizing flow cannot be favorably achieved, and it is difficult to wash the rotatable disk due to the complicated construction thereof. Furthermore, only a coating solution of lower concentration can be used due to the uneven ventilation described above, so that the efficiency of coating is unsatisfactory.
Further, in the apparatuses disclosed in Japanese Patent Publications Nos. 61-8734 and 61-8736, Japanese Patent Application Laid-Open No. 59-95924 and so forth, perforations are disposed at a relatively outer side of a rotatable disk, and, in the apparatuses disclosed by the latter two inventions, air passing through the slit, which is formed between the perforated disk and the wall of the apparatus, and air through the perforated disk can be controlled independently of each other, whereby the above-described disadvantages can be obviated. However, the mechanisms are complicated for obviating the above disadvantages, and the prices of the apparatuses are high.